Various research and development efforts are being paid extensively in the tire manufacturing industry in quest of systems and processes to produce pneumatic tires with improved qualities at enhanced efficiencies. Such efforts are mostly directed at realizing completely automated tire building equipment to make it possible to manufacture pneumatic tires without having recourse to any human intervention.
The demand for improvements is eager and pressing especially in the field of producing green tires from unvalcanized rubbery strips on tire-building drums. This is because of the fact that intricate, highly skilled techniques and knowhows are required in correctly and accurately feeding resilient tire-forming strips and segments to a rotating tire-building drum. Extreme difficulties have thus been encountered in realizing fully automated equipment capable of correctly feeding such yielding materials to a tire-building drum.
One of the prior-art systems to automatically feed rubbery strips to tire-building drums for the manufacture of green tires is taught in Japanese Preliminary Publication of Patent No. 54-131681. In the rubbery-strip feeding apparatus disclosed therein, however, a drawback is pointed out in that the cut segment of a supplied rubbery strip is transferred to a rotating tire-building drum without being retained to any constraining means. If the rubbery strip to be fed to the tire-building drum has a thickness irregularly varying widthwise of the strip or is composed of two or more component strip members or portions formed of different materials, the rubbery strip tends to shrink longitudinally over its opposite side portions and to consequently invite reduction of width longitudinally of the strip. Since, in this instance, the rubbery strip being transferred to the tire-building drum is not constrained from causing such shrinkage, the rubbery strip is unable to maintain its initial thickness and width throughout the length of the cut segment to be applied to the tire-building drum or to any sheet material preliminarily wrapped round the tire-building drum. The present invention contemplates elimination of such a drawback in a prior-art rubbery-strip feeding apparatus of the described general character.